(Reuters) - NetJets, the luxury plane unit of billionaire Warren Buffett's Berkshire Hathaway Inc ( BRK/A ), sued its 3,400-member pilots union for defamation over statements about its commitment to safety and training pilots.

The lawsuit filed on Monday in a state court in Columbus, Ohio, where NetJets is based, seeks unspecified damages.

It follows years of often contentious relations between the carrier and the NetJets Association of Shared Aircraft Pilots.

"NJASAP stands by the concerns we have raised about pilot training and the safety and maintenance cultures--concerns that have only increased in intensity in recent months," the union's president Pedro Leroux said on Wednesday. "We view the lawsuit as an attempt to silence us."

Neither NetJets nor its lawyers immediately responded to requests for comment.

Buffett flies on NetJets planes, and in 2015 told Berkshire shareholders "we have no anti-union agenda whatsoever."

NetJets accused its union of making false and defamatory statements through press releases, newspaper ads and social media to damage its reputation with customers, employees and the public.

It said the statements included suggestions that NetJets' flight planning system was defective, in part because it could send aircraft into dangerous weather, and that the company cared more about saving money than safety.

NetJets also objected to a Jan. 26, 2024 ad in the Wall Street Journal that referenced the recent mid-air cabin panel blowout on an Alaska Airlines plane and said: "NetJets Owners: What if you looked out your window and saw a panel of the plane?"

The company also objected to suggestions that new pilots might be unqualified because they "predominantly" gained flying experience on small planes, and were inadequately trained by NetJets instructors.

In April 2023, the union sued NetJets for allegedly interfering with its communications about contract negotiations.

A federal judge in Columbus dismissed that case in January, saying he lacked jurisdiction and that NetJets "has not struck a fundamental blow to the union."

Berkshire, based in Omaha, Nebraska, employed 396,440 people at year end, including 8,349 at NetJets. Most are not unionized.

The case is NetJets Inc et al v NetJets Association of Shared Aircraft Pilots, Court of Common Pleas, Franklin County, Ohio, No. 24CV004374.